After a journey of nine years and 3 billion miles, NASA's New Horizons spacecraft had a close-encounter with Pluto at 7:50 a.m. EDT July 14, 2015, closing to a distance of about 7,800 miles (12,500 kilometers) from the dwarf planet and its system of five known moons.
The 1,050-pound piano-sized probe was launched January 19, 2006 aboard an Atlas V rocket from Cape Canaveral, Florida.
This photo of Pluto, which lost its designation as the solar system's ninth planet in 2006, was made from four images from New Horizons' Long Range Reconnaissance Imager (LORRI) combined with color data from the Ralph instrument for an enhanced color global view released by NASA on July 24, 2015. The images, taken when the spacecraft was 280,000 miles (450,000 kilometers) away, show features as small as 1.4 miles (2.2 kilometers).
This highest-resolution image released December 5, 2015 reveals new details of Pluto's rugged, icy cratered plains.
The layering in the interior walls of many craters (the large crater at upper right is a good example) are visible.
The darker crater in the lower center is apparently younger than the others, because dark material ejected from within - its "ejecta blanket" - has not been erased and can still be made out.
This image released December 5, 2015 shows great blocks of Pluto's water-ice crust appear jammed together in the informally named al-Idrisi mountains.
Some mountain sides appear coated in dark material, while other sides are bright. Other materials appear crushed between the mountains, as if these great blocks of water ice, some standing as much as 1.5 miles high, were jostled back and forth.
The mountains end abruptly at the shoreline of the informally named Sputnik Planum.
This one of the sharpest views of Pluto that NASA's New Horizons spacecraft obtained during its flyby on July 14, 2015, released December 5. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, revealing features smaller than half a city block on Pluto's diverse surface.
The images include a wide variety of cratered, mountainous and glacial terrains - giving a super-high resolution window to Pluto's geology.
This highest-resolution image released December 4, 2015, shows how erosion and faulting has sculpted this portion of Pluto's icy crust into rugged badlands.
The prominent 1.2-mile-high cliff at the top, running from left to upper right, is part of a great canyon system that stretches for hundreds of miles across Pluto's northern hemisphere.
Pluto's glowing halo
This image of Pluto's full crescent was made just 15 minutes after New Horizons' closest approach to the dwarf planet on July 14, 2015, as the spacecraft looked back at Pluto toward the sun.
Pluto’s Blue Sky
Pluto's haze layer shows its blue color in this picture taken by the New Horizons Ralph/Multispectral Visible Imaging Camera (MVIC).
The high-altitude haze is thought to be similar in nature to that seen at Saturn's moon Titan. The source of both is likely sunlight-initiated chemical reactions of nitrogen and methane.
This image was generated by software that combines information from blue, red and near-infrared images to replicate the color a human eye would perceive as closely as possible.
Pluto's large moon Charon
A stunning color view of Pluto's large moon Charon reveals smooth plains, craters and a huge canyon system that dwarf's the Grand Canyon on Earth.
Pluto global view
This near-full image of Pluto, released by NASA September 24, 2015, provides the best global view yet obtained, a mosaic of images beamed back from the New Horizon's probe during its July flyby of the dwarf planet.
A zoomed-in portion of a new global mosaic showing the full range of Pluto's intriguing terrain, from dark mountainous, heavily cratered zones to the smooth, frozen plains of Sputnik Planum to strangely ridged features that defy easy explanation in this photo released by NASA September 24, 2015.
Pluto's surface ridges
In a scene measuring 330 miles across, strange linear ridges can be seen on Pluto's surface, along with a deep canyon and isolated plains in this photo released by NASA September 24, 2015.
A high-resolution closeup showing the smooth plain of Sputnik Planum butting up against more mountainous terrain in this photo released by NASA September 24, 2015. The dune-like ripples have not yet been explained.
A zoomed-in look at the transition zone between the smooth, icy plains of Sputnik Planum and darker, more mountainous terrain in this photo released by NASA on September 24, 2015.
Pluto's majestic mountains
A closeup view of Pluto's crescent shows 11,000-foot-high mountains bordering the smooth terrain of Sputnik Planum and striking views of the world's atmospheric hazes in a photo taken July 14, 2015 and released by NASA September 17.
Pluto - backlit panorama
A stunning backlit view of Pluto's crescent, shows towering ice mountains, arctic-like plains of nitrogen ice and multiple haze layers extending more than 60 miles above the surface of the dwarf planet in a photo taken July 14, 2015 and released by NASA on September 17.
In this small section of the larger crescent image of Pluto, taken by NASA's New Horizons just 15 minutes after the spacecraft's closest approach on July 14, 2015 and released September 17, the setting sun illuminates a fog or near-surface haze cut by the parallel shadows of many local hills and small mountains. The image was taken from a distance of 11,000 miles (18,000 kilometers), and the width of the image is 115 miles (185 kilometers).
Pluto - Cthulhu Regio region
A "synthetic perspective" view of Pluto based on the latest images from the New Horizons spacecraft, stored on the new Horizon's spacecraft since the historic July 14 flyby and released September 10, 2015, show Pluto as it would appear from an altitude of about 1,100 miles.
This view looks northeast over the dark, heavily cratered Cthulhu Regio region and towards the smooth expanse of icy plains dubbed Sputnik Planum.
Pluto - Sputnik Planum region
A mosaic of images, taken July 14 and released September 10, 2015., shows the left side of the heart-shaped icy plain Sputnik Planum region (the smooth, bright region across the center, with features as small as a half-mile across. The mosaic covers a region roughly 1,000 miles (1600 kilometers) wide.
Pluto - Sputnik Planum
In the center of this 300-mile (470-kilometer) wide image of Pluto from NASA's New Horizons spacecraft, taken July 14 and released September 10, 2015, is the large region of jumbled, broken terrain on the northwestern edge of the vast, icy plain Sputnik Planum, to the right. The smallest visible features are 0.5 miles (0.8 kilometers) in size.
A 220-mile-wide view of Pluto's dark, cratered terrain and surrounding, younger areas that appear to include dunes of some sort in a photo taken in the July 14 flyby of Pluto and released by NASA on September 10, 2015.
Pluto's large moon Charon, taken 10 hours before New Horizons flew past Pluto on July 14. From the NASA caption: "Charon, which is 750 miles in diameter, displays a surprisingly complex geological history, including tectonic fracturing; relatively smooth, fractured plains in the lower right; several enigmatic mountains surrounded by sunken terrain features on the right side; and heavily cratered regions in the center and upper left portion of the disk. There are also complex reflectivity patterns on Charon's surface, including bright and dark crater rays, and the conspicuous dark north polar region at the top of the image."
Pluto sends a breathtaking farewell to New Horizons. Backlit by the sun, Pluto's atmosphere rings its silhouette like a luminous halo in this image taken by NASA's New Horizons spacecraft around midnight EDT on July 15, 2015. This global portrait of the atmosphere was captured when the spacecraft was about 1.25 million miles (2 million kilometers) from Pluto and shows structures as small as 12 miles across. The image, delivered to Earth on July 23, is displayed with north at the top of the frame.
Pluto moons Nix and Hydra
Pluto's tiny moons Nix (left) and Hydra are shown in these enhanced images from the New Horizons Ralph instrument. Nix has a reddish spot that has attracted the interest of mission scientists, with some speculating that the region is the site of a large impact crater.
The images, obtained the morning of July 14, 2015 and released by NASA July 21, were taken from a distance of about 102,000 miles (164,000 kms) from Nix and 143,000 (230,000 kms) miles from Hydra. Features as small as approximately 2 miles (3 kilometers) across on Nix are visible on the moon, which is estimated to be 26 miles (42 kilometers) long and 22 miles (36 kilometers) wide.
Nix and Hydra are the second and third Pluto moons discovered after Charon. Hydra appears lopsided while Nix is "jelly bean-shaped"... very different from moons that dominate the Solar System.
Second mountain range
Pluto's icy mountains have company. NASA's New Horizons mission has discovered a new, apparently less lofty mountain range on the lower-left edge of Pluto's best known feature, the bright, heart-shaped region named Tombaugh Regio (Tombaugh Region).
A newly discovered mountain range lies near the southwestern margin of Pluto's Tombaugh Regio (Tombaugh Region), situated between bright, icy plains and dark, heavily-cratered terrain. This image was acquired by New Horizons on July 14, 2015 from a distance of 48,000 miles (77,000 kilometers) and sent back to Earth on July 20. Features as small as a half-mile (1 kilometer) across are visible.
These newly-discovered frozen peaks are estimated to be one-half mile to one mile (1-1.5 kilometers) high, about the same height as the United States' Appalachian Mountains. The Norgay Montes (Norgay Mountains) discovered by New Horizons on July 15 more closely approximate the height of the taller Rocky Mountains.
Icy mountains of Pluto
A new close-up image, released by NASA July 14, 2015, of a region near Pluto's equator reveals a giant surprise: a range of youthful mountains rising as high as 11,000 feet (3,500 meters) above the surface of the icy body.
The mountains likely formed no more than 100 million years ago -- mere youngsters relative to the 4.56-billion-year age of the solar system.
"This is one of the youngest surfaces we've ever seen in the solar system," says Jeff Moore of New Horizons' Geology Geophysics and Imaging Team (GGI).
Pluto's Tombaugh Regio
Traveling at 30,800 mph, New Horizons captured this image of Pluto from 476,00 miles away on July 13, 2015, around 16 hours ahead of the closest approach.
NASA named the heart-shaped region that is visible here Tombaugh Regio, after the discoverer of Pluto Clyde Tombaugh.
Pluto's flowing ice floes
New Horizons discovered flowing ices at the left edge of Pluto's heart-shaped area seen in this photo released by NASA July 24, 2015. In the northern region of Pluto's Texas-sized plain known as Sputnik Planum (Sputnik Plain), swirl-shaped patterns of light and dark suggest that a surface layer of exotic ices has flowed around obstacles and into depressions, much like glaciers on Earth.
"We've only seen surfaces like this on active worlds like Earth and Mars," said mission co-investigator John Spencer of SwRI. "I'm really smiling."
Pluto and Charon in false color
Not actual photographic images -- Pluto and Charon are shown here in exaggerated colors making it easy to note the differences in surface material and features.
The picture reveals the bright heart-shaped region of Pluto includes areas that differ in color characteristics. The western lobe, shaped like an ice-cream cone, appears peach color in this image. A mottled area on the right (east) appears bluish.
The images were obtained using three of the color filters of the "Ralph" instrument on July 13, 2015. New Horizons has seven science instruments on board the spacecraft--including "Ralph" and "Alice", whose names are a throwback to the "Honeymooners," a popular 1950s sitcom.
How big is Pluto?
Two of the best New Horizons pre-flyby views of Pluto, right, and its large moon Charon show a variety of terrains, from apparent impact craters to cliffs and chasms and distinct polar caps, July 11, 2015. Mission scientists have found Pluto to be 1,473 miles (2,370 km) in diameter, larger than all other known solar system objects beyond the orbit of Neptune. That size makes it two-thirds that of the moon. Measuring Pluto's size has been a decades-long challenge due to complicating factors from its atmosphere.
The International Astronomical Union (IAU) demoted Pluto to dwarf planet status in 2006 not because of its size, however, but because it didn't clear the "neighborhood" of its own orbit, a requirement for planet designation.
Putting Pluto and Charon in perspective
This graphic presents a view of Pluto and Charon as they would appear if placed slightly above Earth's surface and viewed from a great distance.
Recent measurements obtained by New Horizons indicate that Pluto has a diameter of 1,473 miles, 18.5 percent that of Earth's, while Charon has a diameter of 751 miles, 9.5 percent that of Earth's.
New Horizons science team
Members of the New Horizons science team react to seeing the spacecraft's last and sharpest image of Pluto before its closest approach later in the day at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland on July 14, 2015.
The U.S. spacecraft sailed past Pluto July 14, 2015, capping a 3-billion-mile journey to the solar system's farthest reaches.
Pluto on the big screen
People look at an early image of Pluto taken by NASA's New Horizons probe as the craft makes its closest flyby of the dwarf planet at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, July 14, 2015.
The unmanned NASA spacecraft whizzed by Pluto on July 14, making its closest approach in the climax of a decade-long journey to explore the dwarf planet for the first time.
Moving faster than any spacecraft ever built -- at a speed of about 30,800 miles per hour (49,570 kph) -- the flyby happened at 7:49 am (1149 GMT), with the probe running on auto-pilot. It was to pass by Pluto at a distance of 7,767 miles (12,500 kilometers).
New Horizons hat
Tara Kedia wears a New Horizons probe hat at the Johns Hopkins University Applied Physics Laboratory July 14, 2015 in Laurel, Maryland.
The unmanned NASA spacecraft whizzed by Pluto on July 14, making its closest approach in the climax of a decade-long journey to explore the dwarf planet for the first time.
Moving faster than any spacecraft ever built -- at a speed of about 30,800 miles per hour (49,570 kph) -- the flyby happened at 7:49 am (1149 GMT), with the probe running on auto-pilot.
Pluto's big heart
New Horizons' Long Range Reconnaissance Imager (LORRI) provided this photo of Pluto July 7, 2015.
This image has been combined with lower-resolution color information from the Ralph instrument. This view is dominated by the large, bright feature informally named the "heart," which measures approximately 1,000 miles (1,600 kilometers) across. The heart borders darker equatorial terrains, and the mottled terrain to its east (right) are complex. However, even at this resolution, much of the heart's interior appears remarkably featureless -- possibly a sign of ongoing geologic processes.
At two and a half million miles from Pluto, New Horizons took the best image of four dark spots on the planet, July 11, 2015. What continues to pique the interest of scientists is their similar size and even spacing.
The spots appear on the side of Pluto that always faces its largest moon, Charon -- the face that was invisible to New Horizons when the spacecraft made its close flyby the morning of July 14.
New Horizons scientists react to new pictures of Pluto beamed back from the New Horizons probe. Left to right: Cathy Olkin, Jason Cook, Alan Stern, Will Grundy, Casey Lisse and Carly Howett.
Pluto's North Pole, Equator and Central Meridian
For the first time on Pluto, this view from July 11, 2015 reveals linear features that may be cliffs, as well as a circular feature that could be an impact crater.
Rotating into view is the bright heart-shaped feature that would be seen in more detail during New Horizons' closest approach on July 14.
The annotated version includes a diagram indicating Pluto's north pole, equator, and central meridian.
New Horizons and Pluto
An artist's impression of NASA's New Horizons spacecraft encountering Pluto and its largest moon, Charon, is seen in this NASA image from July 2015.
New Horizons is the first spacecraft to visit distant Pluto, a dwarf planet in the solar system's frozen backyard.
Pluto was discovered by Clyde Tombaugh in 1930.
Pluto: first color image
Pluto and its largest moon, Charon, taken by the Ralph color imager aboard NASA's New Horizons spacecraft, is quite small in the distance on April 9, 2015.
This is the first color image ever made of the Pluto system by a spacecraft on approach, according to NASA.
The image was made from a distance of about 71 million miles (115 million kilometers), roughly the distance from the Sun to Venus. At this distance, neither Pluto nor Charon is very clear in color, but their distinctly different appearances are visible.
The surface of Pluto
A combination picture of the most detailed view to date of the entire surface of the dwarf planet Pluto, as constructed from multiple NASA Hubble Space Telescope photographs taken from 2002 to 2003 are seen in these images released on February 4, 2010.
Hubble reveals a complex-looking and variegated world with white, dark-orange, and charcoal-black terrain.
The overall color is believed to be a result of ultraviolet radiation from the distant sun breaking up methane present on Pluto's surface, leaving behind a dark, molasses-colored, carbon-rich residue.
This series of pictures took four years and 20 computers operating continuously and simultaneously to accomplish.
Artist rendering of Pluto's night region
In this artist rendering, Pluto's largest moon Charon rises over the frozen south pole surface of Pluto, casting a faint silvery luminescence across the distant planetary landscape.
On July 14, 2015, New Horizons mission scientists aimed to obtain the first images of the night region of Pluto, using only the light from Charon, itself softly illuminated by a Sun 1,000 times dimmer than it is at Earth.
The images will provide New Horizons' only view of Pluto's lesser-known south polar region, currently in the midst of a numbingly-long winter. "The only way for New Horizons to observe Pluto's elusive night region is to see it in 'Charonshine,'" says Cathy Olkin, New Horizons deputy project scientist. "It's almost time for the big reveal, and I couldn't be more excited."
Pluto, marked by an arrow, is tiny in this September 2006 photo taken by the New Horizons spacecraft at a distance of 2.6 billion miles away.
An artist's impression of NASA's New Horizons spacecraft en route to Pluto.
After nine years and a journey of 3 billion miles (4.8 billion km), NASA's New Horizons robotic probe was programmed to be awoken from hibernation to begin its unprecedented mission: the study of the icy dwarf planet Pluto and its home, the Kuiper Belt.
A pre-set alarm clock roused New Horizons from its electronic slumber at 3 p.m. EST (2000 GMT) on December 6, 2014.
The New Horizons spacecraft lifts off aboard an Atlas V rocket at Cape Cnaveral, Florida, January 19, 2006.
The 1,050-pound piano-sized probe is set for a July 14 flyby with the dwarf planet Pluto at a distance of about 7,800 miles (12,500 kilometers). The probe is traveling 30,800 mph as it approaches.